German Auslegeschrift 24 23 111 discloses a "device for reducing harmful components in the exhaust gas of internal combustion engines". There, a continuously operating fuel injection system is disclosed in which the air throughput in the air intake tube is continuously measured and, together with further operating variables, it is processed to make a control signal for the fuel quantity. The electrical portion of the known apparatus includes the serial disposition of a sawtooth voltage generator, a comparator, and an end stage for an incrementally triggered magnetic valve for controlling the fuel pressure. The input variables of the comparator, in addition to the sawtooth voltage, are individual signals derived from operating variables of the engine and prepared at a summing point. In the more recent German application P 24 37 713.7, an example for one of the signals operating at the summing point is given. It is proposed in this application to provide a hot-starting enrichment for the fuel metering system in such a manner that a monostable multivibrator emits an output pulse whose length is dependent on temperature, and this pulse is then stored in memory in this summing point.
Thus for each correction, the prior art provides a corresponding signal generation. With a view, however, to the most cost-favorable means of mass production of fuel metering systems, the known systems have proven not to be optimal.